The Era of the knock knock joke

It happened somewhere along I55, heading North towards my moms. The dreaded knock knock jokes.
Marcus was first
Knock Knock
Who's there?
R.V.
R.V who?
R.V there yet?

Okay, now see? That was funny. I forgot the number one rule of motherhood. Never, ever, ever, under no circumstances, ever, should you laugh at any joke. I laughed. And I bear the consequences even today.

Weston heard me laugh and he wants to make me laugh too and so, he takes his turn.
Knock Knock.
Who's there?
R.V.
R.v who?
blanket.

Trust me, my life is over. But in a grand attempt to save me from the forever land of RV knock knock jokes, Esther takes her turn.
Knock Knock.
Who's there?
Pee Pee head.
(sigh) Pee Pee head who?
R.V.

This is met with peals of uncontrollable laughter on the part of all three kids. All three of them have repeated this same trio of jokes all morning, every once in a while throwing in something, equally as ridiculous.
The Era of child joke telling is something akin to torture for a mother. Don't believe me? Today I was expected to laugh at the following:
Why did the chicken shave it's hair? Because he wanted to kill himself.

Why did the horse eat his food? Because he was hungry.

Why did the football player throw a basketball into a cake and pick the cake up to make a touchdown? Because he thought the cake was a ball.